Device for promoting metallurgical reactions

ABSTRACT

A device for accelerating the physical and chemical processes in metallurgical metallic melts or similar dense media of elevated temperatures includes a rotatable stirrer which is adapted to dip into the melt. In accordance with the invention, the stirrer includes a central suction pipe and a plurality of radially outwardly extending ejection ducts connected into the suction pipe at the upper end thereof. A feature of the construction is that the ejection ducts are defined in a disclike member which, at least on the side carrying the suction pipe, is formed as a smooth solid body of a refractory material and the suction pipe, is formed as a smooth solid body of a refractory material and the suction pipe is connected axially symmetrical thereto. In one embodiment, the underside of the solid body has a polygonal base in order to facilitate the stirring action on the melt. Ejection ducts advantageously terminate at the corners of the polygonal solid body. In some instances, it is also desirable to form the top side with projections or flat edges for entraining the melt and the slag and for aiding in its intermixing.

I United States Patent 1 1 3,595,547

[72] Inventors Hubert Polomsky 2,976,7ll 3/196] Smith i 259/95 Duisburg-Buchholz; 3,278,295 /1966 Ostberg et al 266/34 Gerhard Eichbaum, Duisburg, both of, FOREIGN PATENTS Germany 1 2331? 21:22: 2:22: 222422 Filed Feb'51969 y Patented July 27, 1971 Primary Examiner Gerald A. Dost [73] Assignee Demag A G Attorney-McGlcw and Toren Duisburg, Gennany [32] Priority Feb. 23, I968 [33] Germany ABSTRACT: A device for accelerating the physical and 3 p 5 3 77 4 chemical processes in metallurgical metallic melts or similar dense media of elevated temperatures includes a rotatable stirrer which is adapted to dip into the melt. ln accordance [54] DEVICE FOR PROMOTING METALLURGICAL with the invention, the stirrer includes a central suction pipe REACTIONS and a plurality of radially outwardly extending e ection ducts 7 Claims, 4Drawing Figs connected mto the suctlon pipe at the upper end thereof. A feature of the construction Is that the e ection ducts are [52] U.S. Cl 266/34 A, d fi d in a disclike member which, at least on h i can) 1 259/95 ing the suction pipe, is formed as a smooth solid body of a [5 l Int. Cl C2lc 7/00 refractory material and the suction pipe, is f d as a Smooth Field of Search... 266/34, 34 Solid body f a f tor i l and the suction pipe is con- 34 i 39; /50, 61; 259/ nected axially symmetrical thereto. In one embodiment, the underside of the solid body has a polygonal base in order to [56] References cued facilitate the stirring action on the melt. Ejection ducts ad- UNITED STATES PATENTS vantageously terminate at the comers of the polygonal solid 651,608 6/1900 Norcross 259/95 body. In some instances, it is also desirable to form the top 2,397,737 4/ 1946 Heuer 75/55 side with projections or flat edges for entraining the melt and 2,660,525 I 1/ l953 Foster 266/24 the slag and for aiding in its intermixing.

PATENTFUJULP7|QH 3'595'5A7 sum 1 0F 3 \NVENTORS Hubert POLOMSKY B Gerhard EICHBAUM Y 1 a their ATTORNEYS PATENTEUJULZYIBYI 3.595.547

sum 2 OF 2 FIGA INVENTORS Hu bert POLOMSKY Gerhard EICHBAUM their ATTORNEYS DEVICE FOR PROMOTING METALLURGICAL REACTIONS SUMMARY OF THE INVENTION] This invention relates, in general, to the construction of stirring devices for reaction products and particularly to a new and useful metallurgical stirrer which is adapted to be positioned into a metal melt and which includes an upper soliddisc portion having discharge passages which are adapted to be located adjacent a slag layer on the melt, and which is connected to a suction pipe at its axial center.

It is known to employ stirring devices for facilitating the reaction process of a metal melt in a metallurgical plant. The stirrer serves substantially for desulfurizing, dephosphorizing, and desiliconizing pig iron melts. The pig iron melts are of a type which require a particular degree of purity. The amount of pure pig iron which is required in recent years has considerably increased and it is employed as a standard material for the foundry and for the steel industry. The pig iron produced in the blast furnace is mixed with additions of lime, soda, or calcium carbide and the accompanying substances of pig iron can be removed to a certain degree in a correspondingly accelerated reaction by the use of a stirrer.

The known stirrer constructions act like a centrifugal pump and, in addition, the pig iron is mixed by a rotating device while gas bubbles are forced to the surface and an intimate contact takes place between the slag layer and theremaining portion of the melt. The productionof larger quantities of purified pig iron require an accelerated reaction. The speed of rotation of the stirrer is thus generally increased when an increased output is desired. 7

With increased speed of stirrer operation there is an increase of load on the stirrer. The stirrers which comprise substantially a vertical suction pipe and at least two ejection pipes extending horizontally outwardly from the suction pipe in the form of a T-shaped configuration are of only moderate strength. Because of thermal stresses in the viscosity of the melt, there is a large torque acting on these stirrers to produce a very large bending moment at the location of the intersection of the radial ejection or discharge passages with the central suction passage. Very large sized stirrers will generally wear at the location of the connection of the radial passages to the suction passage and this point will wear prematurely due to the fatigue of the material. Because of the high temperatures of operation, a portion of the device must be made of a temperature-resistant material such as a ceramic'material and this portion must be made with great care.

The present invention provides an improved construction of the stirrer which will facilitate the reduction of stress on the various portions thereof and, particularly, in the area of the junction of the radial discharge passages to the central suction passage. This is achieved by forming the radial passages in a solid disclike element having at least the side facing the suction conduit formed as a smooth solid body of refractory material. The construction permits operation at highspeeds with relatively low friction between the stirrer and the metallurgical bath material. Therefore, the stress forces acting on the stirrer are reduced and, in addition, a device may be operated in either direction of rotation without any deleterious results in respect to mixing or wear on the stirrer. The disc-shape also provides a better equalization of the material during acceleration and deceleration. 1

Essential for the construction of stirrers of this type is that the stirrer element combine a pumping mechanism with a stirring mechanism. The pumping mechanism includes the central suction pipe which is effective to draw up the metallurgical melt material and to discharge it out through the radially extending ejection passages which complete the pumping cycle but which also provide a stirring action on the melt material. By constructing the passages within a solid body such as a disc, it is possible to improve the stirring action by forming the solid body with sidewalls which will produce a whirling effect in the contact zone between the slag layer and the melt proper.-The top surface or the bottom surface may be formed as a polygonal solid and the location of the solid within the melt will determine the type of stirring action and pumping action which may be obtained. The ejection ducts may advantageously terminate at the corners of the polygonal solid body. The corners are particularly suitable for moving slag parts and the melt material will flow outwardly adjacent the corners to further increase the intermittent contact of the reaction materials.

Despite the construction of the disc body with a smooth underside, as suggested by the invention, it is possible to provide the top side of the solid body with edges, projections, etc., for entraining melt and slag material. Any slag portions which move into the range of these edges are carried along and conveyed by the melt, and come in contact with the melt on all sides.

Accordingly, it is an object of the invention to provide an improved device for facilitating reactions in a metallurgical melt bath and which includes a stirrer having a central tubular member forming a suction passage and a disclike solid member forming a plurality of ejection passages connecting into the upper end of the suction passage.

A further object of the invention is to provide a stirrer for metallurgical reactors which includes a central solid portion defining an ejection passage which communicates with a central suction passage which extends downwardly therefrom, the solid portion being formed with a smooth surface on the side facing the suction passage and preferably having means on its opposite side for facilitating the stirring action.

A- further object of the invention is to provide a stirrer for metallurgical reaction which is simple in design, rugged in construction and economical to manufacture. I

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the Drawings:

FIG. 1 is a partial axial sectional view of a metallurgical bath having a stirrer constructed in accordance with the invention; and

FIG. 2 is a top plan view of the stirrer shown in FIG. 1

FIG. 3 is a top plan view with a central broken away portion of another embodiment of stirrer; and

FIG. 4 is a bottom plan view of the stirrer shown in FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, in particular, the invention embodied therein in FIG. 1 comprises a stirrer generally designated I which is mounted in a cover member or similar holder (not shown) above a metallurgical vessel 3 having a melt bath 2. The stirrer I is arranged so that it dips into the melt 2. The vessel 3 is advantageously a simple ladle or a reaction vessel which has a cover (not shown) in which is arranged a rotary support for the rotating stirrer 1.

In accordance with the invention, the stirrer 1 includes a central solid disc or base portion 9 which defines a plurality of substantially radially located passages or ejection ducts 7 and 8. Pairs of the ducts 7 and 8 are advantageously arranged at right angles to each other in a cross formation. The solid disc 9 which defines the ejection ducts 7 and 8 is provided with a smooth underside 10. A suction pipe or suction conduit 4 is joined to the central underside of the disc 9'and a suction passage 5 defined therein communicates at its upper end 6 with inner ends of the passages 7 and 8.

ln the embodiment indicated in FIGS. 3 and 4, there is provided a stirrer generally designated 1' which is of a construction which is substantially similar to that indicated in FIG. I, but which includes an underside which is formed smoothly as the other embodiment, but which is of a polygonal construction having walls 11 forming a rectangle or square. In this con struction, the ejection ducts 7' and 8' advantageously terminate at their outer or discharge ends at the corners of the polygonal underside formation. The edges 12 thus obtained serve to stir the melt by contact in the slag when the stirrer is lowered to the level indicated in FIG. 1, in which the upper edge 13 of the stirrer is substantially flush with the slag layer 14. Vertical adjustment of the stirrer l in each embodiment is advantageously carried out by the mounting of the driving rod or shaft 15 which transmits the rotary movement. The rotary drive is not represented, but comprises substantially an electromotor and a driving reduction gear which are both arranged on a cover (not represented).

It is advisable to locate the center of the ejection ducts 7 and 8 so that they discharge to the underside of the slag layer 14. In this manner, the slag portions which are brought up from the depths of the molten bath 2 are flushed along the underside of the slag layer.

The polygonal shape may be such that the corners are defined by the outer ends of the passages 7' or 8' or the passages may extend outwardly beyond the corners. In all the embodiments, the underside 10 is formed as a smooth solid body and this results in a reduced wear, reduced friction and reduced driving power requirements.

What I claim is:

' l. A device for accelerating the physical and chemical processes in a metallurgical melt comprising a rotatable stirrer including a disc portion having a stirring edge which is adapted to be located adjacent the surface of the bath and a suction pipe connected centrally to and extending downwardly from said disc portion, said disc portion defining a plurality of ejection passages therein which terminate in discharges at the periphery of said disc portion and which are connected at their inner ends to the upper end of said suction pipe, said disc portion having at least on the side adjacent said suction pipe a smooth surface of refractory material.

2. A device, according to claim I, wherein said disc portion has a polygonal base.

3. A device, according to claim I, wherein said ejection passages terminate in radially outwardly extending discharges, said disc portion defining at least on its side adjacent said suction pipe, a polygonal solid body portion terminating in corners adjacent the discharges of said ejection ducts.

4. A device, according to claim 1, wherein said disc portion has entrainment means defined adjacent the upper edge thereof for entraining the melt and slag material.

5. A device, according to claim 4, wherein said means com prises projecting surfaces.

6. A device, according to claim 1, wherein said disc portion includes a top frustoconical central portion and a rotatable shaft portion at the upper end of said frustoconical portion, and a flat substantially horizontal intermediate portion extending radially outwardly from said frustoconical portion and adapted to be located adjacent the surface of the slag layer of the melt.

7. A device, according to claim 6, wherein there are at least four separate ejection ducts defined in said disc portion extending substantially radially outwardly from said suction pipe and each being at right angles to each other, said ejection ducts extending upwardly and outwardly to a radial discharge. 

2. A device, according to claim 1, wherein said disc portion has a polygonal base.
 3. A device, according to claim 1, wherein said ejection passages terminate in radially outwardly extending discharges, said disc portion defining at least on its side adjacent said suction pipe, a polygonal solid body portion terminating in corners adjacent the discharges of said ejection ducts.
 4. A device, according to claim 1, wherein said disc portion has entrainment means defined adjacent the upper edge thereof for entraining the melt and slag material.
 5. A device, according to claim 4, wherein said means comprises projecting surfaces.
 6. A device, according to claim 1, wherein said disc portion includes a top frustoconical central portion and a rotatable shaft portion at the upper end of said frustoconical portion, and a flat substantially horizontal intermediate portion extending radially outwardly from said frustoconical portion and adapted to be located adjacent the surface of the slag layer of the melt.
 7. A device, according to claim 6, wherein there are at least four separate ejection ducts defined in said disc portion extending substantially radially outwardly from said suction pipe and each being at right angles to each other, said ejection ducts extending upwardly and outwardly to a radial discharge. 